Direct positive silver halide emulsions containing trimethine cyanine dyes



United States Patent US. Cl. 96-106 13 Claims ABSTRACT OF THE DISCLOSURETrimethine cyanine dyes are provided which contain a 3-indole nucleuswhich contains either a fused aromatic ring, an alkylene bridge or aZ-heterocyclic substituent. Direct positive emulsions containing thesedyes are also provided.

This application is a continuation-in-part of our copending US. patentapplication Ser. No. 609,792, filed J an. 17, 1967, now abandoned, andentitled, Photographic Materials.

This invention relates to novel cyanine dyes, and to new and improveddirect positive photographic silver halide emulsions containing certaincyanine dyes.

We have found certain trimethine cyanine dyes which are outstandingspectral sensitizers in direct positive type photographic silver halideemulsions. They provide superior reversal systems, especially withfogged silver halide emulsions, that are characterized by both goodspeed and desired sensitivity to radiation up to wavelengths in therange of about -650-740 mg with maximum sensitivity occurring in mostcases in the region of about 630-680 m They are further characterized byincreased water solubility and are much better sensitizers in thepresence of color forming coupler dispersions, as compared with thecorresponding dyes from known 1-alkyl-2-pheny1 indoles.

It is, accordingly, an object of this invention to provide a new classof improved and novel, direct positive photographic silver halideemulsions, and more particularly fogged emulsions of this type,containing at least one of the cyanine dyes of the invention. Anotherobject of this invention is to provide novel emulsions as abovecontaining, in addition, a photographic color former. Another object ofthis invention is to provide novel light-sensitive photographic elementscomprising a support material having thereon at least one layer of thenovel emulsions of the invention. Another object of this invention is toprovide novel cyanine dyes containing certain indole nuclei. Otherobjects of this invention will be apparent from this disclosure and theappended claims.

In accordance with this invention, we prepare our new class of improvedand novel, direct positive photographic silver halide emulsions byincorporating one or more of the cyanine dyes of the invention into asuitable fogged silver halide emulsion. The emulsion can be fogged inany suitable manner, such as by light or with chemical fogging agents,e.g., stannous chloride, formaldehyde, thiourea dioxide and the like.The emulsion may be fogged by the addition thereto of a reducing agentsuch as thiourea dioxide and a compound of a metal more electropositivethan silver such as a gold salt, for example, potassium chloroaurate, asdescribed in British Patent 723,019 (1955).

Typical reducing agents that are useful in providing such emulsionsinclude stannous salts, e.g., stannous chloride, hydrazine, sulfurcompounds such as thiourea dioxide, phosphonium salts such as tetra(hydroxymethyl) phosphonium chloride, and the like. Typical useful metalcompounds that are more electropositive than silver in- 3,501,312Patented Mar. 17, 1970 clude gold, rhodium, platinum, palladium,iridium, etc., preferably in the form of soluble salts thereof, e.g.,potassium chloroaurate, aun'c chloride, (NH PdCl and the like.

Useful concentrations of reducing agent and metal compound (e.g., metalsalt) can be varied over a considerable range. As a general guideline,good results are obtained using about .05 to 40 mg. reducing agent permole of silver halide, and 0.5 to 15.0 mg. metal compound per mole ofsilver halide. Best results are obtained at lower concentration levelsof both reducing agent and metal compound.

The concentration of added dye can vary widely, e.g., from about 50 to2000 mg. and preferably from about 400 to 800 mg. per mole of silverhalide in the direct positive emulsions.

As used herein, and in the appended claims, fogged refers to emulsionscontaining silver halide grains which produce a density of at least 0.5when developed, without exposure, for 5 minutes at 68 F. in KodakDeveloper DK-50 having the composition set forth below, when theemulsion is coated at a silver coverage of 50 mg. to 500 mg. per squarefoot.

Water to make 1.01.

The dyes of this invention are also advantageously incorporated indirect positive emulsions of the type in which a silver halide grain hasa water-insoluble silver salt center and an outer shell composed of afogged waterinsoluble silver salt that develops to silver withoutexposure. The dyes of the invention are incorporated, preferably, in theouter shell of such emulsions. These emulsions can be prepared invarious Ways such as those described in Berriman US. Patent 3,367,778,issued Feb. 6, 1968. For example, the shell of the grains in suchemulsions may be prepared by precipitating over the core grains alight-sensitive water-insoluble silver salt that can be fogged and whichfog is removable by bleaching. The shell is of sufiicient thickness toprevent access of the developer used in processing the emulsions of theinvention to the core. The silver salt shell is surface fogged to makedevelopable to metallic silver with conventional surface imagedeveloping compositions. The silver salt of the shell is sufficientlyfogged to produce a density of at least about 0.5 when developed for 6minutes at 68 F. in Developer A below when the emulsion is coated at asilver coverage of mg. per square foot. Such fogging can be effected bychemically sensitizing to fog with the sensitizing agents described forchemically sensitizing the core emulsion, high intensity light and thelike fogging means well known to those skilled in the art. While thecore need not be sensitized to fog, the shell is fogged. Fogging bymeans of a reduction sensitizer, a noble metal salt such as gold saltplus a reduction sensitizer, a sulfur sensitizer, high pH and low pAgsilver halide precipitating conditions, and the like can be suitablyutilized. The shell portion of the subject grains can also be coatedprior to fogging.

DEVELOPER A Grams M-methyl-p-aminophenol sulfate 2.5 Ascorbic acid 10.0Potassium metaborate 35.0 Potassium bromide 1.0

Water to 1 liter. pH of 9.6.

Before the shell of water-insoluble silver salt is added to the silversalt core, the core emulsions are first :hemically or physically treatedby methods previously lescribed in the prior art to produce centerswhich promote the deposition of photolytic silver, i.e., latent imagenucleating centers. Such centers can be obtained by various techniquesas described herein. Chemical sensitization techniques of the typedescribed by Antoine Hautot and Henri Saubeneir in Science et IndustriesPhotographiques, vol. XXVIII, January 1957, pages 1 to 23 and January1957, pages 57 to 65 are particularly useful. Such chemicalsensitization includes three major classes, namely, gold or noble metalsensitization, sulfur sensitization, such as by a labile sulfur compoundand reduction sensitization, e.g., treatment of the silver halide with astrong reducing agent which introduces small specks of metallic silverinto the silver salt crystal or grain.

The dyes of this invention are highly useful electron acceptors in highspeed direct positive emulsions comprising fogged silver halide grainsand a compound which accepts electrons, as described and claimed inIllingsworth U.S. patent application Ser. No. 619,936 filed Mar. 2,1967, and entitled, Photographic Reversal Materials Case C. The foggedsilver halide grains of such emulsions are such that a test portionthereof, when coated as a photographic silver halide emulsion on asupport to give a maximum density of at least about one upon processingfor six minutes at about 68 F. in Kodak DK-50 developer, has a maximumdensity which is at least about 30% greater than the maximum density ofan identical coated test portion which is processed for six minutes atabout 68 F. in Kodak DK- 50 developer after being bleached for aboutminutes at about 68 F. in a bleach composition of:

Potassium cyanide50 mg. Acetic acid (glacial)3.47 cc. Sodiumacetate-11.49 g. Potassium bromide--119 mg. Water to 1 liter.

The grains of such emulsions will lose at least about and generally atleast about of their fog when bleached for ten minutes at 68 F. in apotassium cyanide bleach composition as described herein. This fog losscan be illustrated by coating the silver halide grains as a photographicsilver halide emulsion on a support to give a maximum density of atleast 1.0 upon processing for six minutes at about 68 F. in Kodak DK-50developer and comparing the density of such a coating with an identicalcoating which is processed for six minutes at 68 F. in Kodak DK-50developer after being bleached for about 10 minutes at 68 F. in thepotassium cyanide bleach composition. As already indicated, the maximumdensity of the unbleached coating will be at least 30% greater,generally at least 60% greater, than the maximum density of the bleachedcoating.

The silver halides employed in the preparation of the photographicemulsions useful herein include any of the photographic silver halidesas exemplified by silver bromide, silver iodide, silver chloride, silverchlorobromide, silver bromoiodide, silver chlorobromide, and the like.Silver halide grains having an average grain size less than about onemicron, preferably less than about 0.5 micron, give particularly goodresults. The silver halide grains can be regular and can be any suitableshape such as cubic or octahedral, as described and claimed inIllingsworth U.S. patent application Ser. No. 619,909 filed Mar. 2,1967, and entitled, Direct Positive Photographic Emulsions Case A. Suchgrains advantageously have a rather uniform diameter frequencydistribution, as described and claimed in Illingsworth U.S. patent aplication Ser. No. 61 ,948. filed Mar. 2, 1967, and entitled,Photographic Reversal Emulsions Case B. For example, at least by weight,of the photographic silver halide grains can have a diameter which iswithin about 40%, preferably within about 30% of the mean graindiameter. Mean grain diameter, i.e., average grain size, can bedetermined using conventional methods, e.g., as shown in an article byTrivelli and Smith entitlted, Empirical Relations Between Sensitometricand Size-Frequency Characteristics in Photographic Emulsion Series, inThe Photographic Journal, vol. LXXIX, 1949, pp. 330338. The foggedsilver halide grains in these direct-positive photographic emulsions ofthis invention produce a density of at least 0.5 when developed withoutexposure for five minutes at 68 F. in Kodak KD-SO' developer when suchan emulsion is coated at a coverage of 50 to about 500 mg. of silver persquare foot of support. The preferred photographic silver halideemulsions comprise at least 50 mole percent bromide, the most preferredemulsions being silver bromoiodide emulsions, particularly thosecontaining less than about ten mole percent iodide. The photographicsilver halides can be coated at silver coverages in the range of about50 to about 500 milligrams of silver per square foot of support.

In the preparation of the above photographic emulsions, the dyes,reducing agents and metal compounds of the invention are advantageouslyincorporated in the washed, finished silver halide emulsion and should,of course, be uniformly distributed throughout the emulsion. The methodsof incorporating dyes and other addenda in emulsions are relativelysimple and well known to those skilled in the art of emulsion making.For example, it is convenient to add them from solutions in appropriatesolvents, in which case the solvent selected should be completely freefrom any deleterious effect on the ultimate light-sensitive materials.Methanol, isopropanol, pyridine, water, etc., alone or in admixtures,have proven satisfactory as solvents for this purpose. The type ofsilver halide emulsions that can be sensitized with the new dyes includeany of those prepared with hydrophilic colloids that are known to besatisfactory for dispersing silver halides, for example, emulsionscomprising natural materials such as gelatin, albumin, agar-agar, gumarabic, alginic acid, etc., and hydrophilic synthetic resins such aspolyvinyl alcohol, polyvinyl pyrrolidone, cellulose ethers, partiallyhydrolyzed cellulose acetate, and the like.

The dyes, reducing agents and metal compounds of the invention can beused with emulsions prepared with any of the light-sensitive silverhalide salts including silver chloride, silver bromide, silverchlorobromide, silver bromoiodide, silver chlorobromoiodide, etc.Particularly useful for direct positive fogged emulsions in which thesilver salt is a silver bromohalide comprising more than 50 mole percentbromide. As indicated previously, the dyes of this invention are alsouseful in emulsions which contain color formers. This is unexpectedsince related prior art dyes cannot be used in emulsions containing acolor former.

The novel emulsions of this invention may be coated on any suitablephotographic support, such as glass, film base such as celluloseacetate, cellulose acetate butyrate, polyesters such as polyethyleneterephthalate, paper, baryta coated paper, polyolefin coated paper,e.g., polyethylene or polypropylene. coated paper, which may be electronbombarded to promote emulsion adhesion to produce the novel photographicelements of the invention.

The novel cyanine dyes of this invention include those having two indolenuclei, each representative nucleus being joined through the 3-carbonatom thereof to one of the respective terminal carbon atoms of atrimethine chain, at least one of said nuclei being 2-aromaticallysubstituted and having a substituent selected from (1) a fusednon-heterocyclic aromatic ring, e.g., a fused benzene ring, a tached tothe benzene ring of the indole nucleus,

(2) a 1,7-alkylene bridge, e.g., a 1,7-trimethylene bridge, and (3) aheteocyclic aromatic nucleus, e.g., a pyridyl nucleus, attached to the2-,carbon atom of the indole nucleus.

More particularly the novel cyanine dyes of our invention include thoserepresented by the following general formula:

wherein A represents a substituent such as a nonheterocyclic arylradical, e.g., phenyl, tolyl, chlorophenyl, methoxyphenyl,3,4-dichlorophenyl, napthyl, etc., or a heterocyclic radical containingfrom 5 to 6 atoms wherein the heteroatom is selected from nitrogen,sulfur, selenium or oxygen, e.g., 2-, 3- or 4-pyridyl, 2-furyl,2-thienyl, etc. (including their quaternary salts such as 3-pyridylmethobromide, 4-pyridyl methiodide, etc.); R and R each represents asubstituent such as hydrogen, an alkyl radical preferably containingfrom 1 to 4 carbon atoms, e.g., methyl, ethyl, propyl, isopropyl, butyl,hexyl, decyl, etc., or a halogen atom, e.g., chlorine or bromine, andtaken together, the atoms necessary to complete a fused nonheterocyclicaromatic ringhaving 6 carbon atoms, e.g., a fused benzene ring; Rrepresents a substituent such as an alkyl radical (including substitutedalkyl) and preferably containing from about 1 to 8 carbon atoms, such asmethyl, ethyl, propyl, butyl, octyl, sulfoalkyl such as sulfopropyl orsulfobutyl, sulfatoalkyl such as sulfatopropyl or sulfatobutyl, orcarboxyalkyl such as carboxyethyl or carboxybutyl; R represents asubstituent selected from the values given for R and, taken togetherwith R an alkylene bridge such as trimethylene or dimethylene; Xrepresents an anion, preferably an anion such as chloride, bromide,iodide, p-toluenesulfonate, thiocyanate, sulfamate, methyl sulfate,ethyl sulfate, perchlorate, etc.; and A R R R and R each are selectedfrom same values, respectively, as A, R R R and R and Z and Y eachrepresents a substituent such as hydrogen, an alkyl radical preferablycontaining from 1 to 4 carbon atoms, e.g,, methyl, ethyl, butyl, hexyl,decyl, etc., and an aromatic radical (including aromatic heterocyclic),e.g., phenyl, tolyl, naphthyl, thienyl, etc.; and wherein at least oneof said defined indole nuclei contains a substituent such as saidheterocyclic radical, said fused non-heterocyclic aromatic ring or saidalkyllene bridge.

The above-defined cyanine dyes of the invention can be convenientlyprepared by condensing an indole represented by the general formula:

wherein A, R R R and R are as previously defined, with v al,l,3-trialkoxy-2-propene, e.g., trimethoxy-Z- propene, in the presenceof mineral acid, to give the symmetrical. cyanine dyes of the invention.

To prepare theunsymmetrical cyanine dyes of the invention a 3-forrnylindole having the formula:

"7 CH0 L wherein A, R R R and R are as previously defined, is condensedwith an ethylenic indole having the formula:

wherein A, R R R and R are as previously defined, and R represents asubstituent selected from the values given for previously defined Z andY. Condensation in the presence of acid, such as HCl, HBr, HClO etc.,gives the cyanine dye salt. The intermediate compounds of Formula IVabove can be prepared from the corresponding ketones (prepared asdescribed in Wolf et al., German Patent No. 614,326) by reaction withGrignard compounds convert them to ethylenes.

The above condensation reactions are advantageously carried out in aninert solvent medium such as, for example, hot glacial acetic acid, inthe presence of a strong mineral acid such as HCl, HBr, HClO etc. Insome cases, the reaction is advantageously heated at reflux temperaturefor short periods. After cooling, the products are precipitated from thereaction mixtures by the addition of nonsolvents such as acetone, ether,etc., and then purified by one or more recrystallizations from suitablesolvents such as, for example, methanol acidified with acids such asabove mentioned. The reactants can be employed in approximatelystoichiometrically calculated equivalents, but advantageously the1,1,3-trialkoxy-2-propene is used in substantial excess of calculatedequivalence for the best results.

The invention is further illustrated by the following examples.

EXAMPLE 1 1,1-dimethyl-2,2'-di- (3-pyridyl)-3,3-indolocarbocyaninebromide dihydrobromide HBr-N I N-HBr l-methyl 2 (3-pyridyl)indole (1.04g., 2 mol.) was dissolved in hot glacial acetic acid (10 ml.).Trimethoxypropene (1.0 g., 1 mol. +200%) was added, followed by thedropwise addition of cone. HCl (1 ml.). The mixture was allowed to standat room temperature for 2 hrs., then diluted with acetone and the solidc0llected. The dye was dissolved in hot methanol ml.) +48% HBr (1.5ml.), filtered and the dye allowed to crystallize. The yield of dye was0.27 g. (16%), M.P. 287-8 C. dec.

A gelatin silver bromoiodide emulsion (2.5 mole percent of the halidebeing iodide) and having an average grain size of about 0.2 micron isprepared by adding an aqueous solution of potassium bromide andpotassium iodide, and an aqueous solution of silver nitrate,simultaneously to a rapidly agitated aqueous gelatin solution at atemperature of 70 C., over a period of about 35 minutes. The emulsion ischill-set, shredded and washed by leaching with cold water in theconventional manner. The emulsion is reduction-gold fog ged by firstadding 0.2 mg. of thiourea dioxide per mole of silver and heating for 60minutes at 65 C. and then adding 4.0 mg. of potassium chloroaurate permole of silver and heating 7 for 60 minutes at 65 C. The above prepareddye, 1,1- dimethyl 2,2 di (3 pyridyl) 3,3 indolocarbocyanine bromidedihydrobromide was then added to the above fogged emulsion in amountsufficient to give a concentration of 0.176 gram of the dye per mole ofsilver. The resulting emulsion was then coated on a cellulose acetatefilm support at a coverage of 100 mg. of silver and 400 mg. of gelatinper square foot of support.

A sample of the coated support was then exposed on an Eastman I-bsensitometer using a tungsten light source and processed for 6 minutesat room temperature in Kodak D-19 developer which has the followingcomposition:

Water to make 1.0 liter.

then fixed, washed and dried. The results are listed in Table Ihereinafter. Referring thereto, it will be seen that the dye of thisexample had a minimum density in exposed areas of only 0.10, asensitivity range up to 680 my and a maximum sensitivity at 635 mu,whereas the control sample similarly prepared and tested but containingno spectral sensitizing dye increased in density with exposure. Thisresult indicates that the dye compound of the above example isespecially well suited to function as a spectral sensitizer. It thusprovides excellent quality direct positive photographic silver halideemulsions. Excellent magenta images were obtained when the color former1-(2,4,6 trichlorophenyl) 3,3 (2", 4" di tamylphenoxyacetamido)benzimidazo 5- pyrazolone was incorporated in theemulsion of this example, the emulsion coated on a support, exposed to atungsten source through Wratten filter No. 61 and No. 16, and reversalprocessed as described in Graham et al. US. Patent 3,046,129, issuedJuly 24, 1962, in Example (a) C01. 27, lines 27 et seq. except thatblackand-white (MQ) development Was omitted, the color development wasreduced to one mnute and was conducted in total darkness until afterfixing.

EXAMPLE 2 l,1'-dimethyl-2,2'-di-(3-pyridyl methobromide)-3,3'-indolocarbocyanine bromide l-methyl 2 (3-pyridy1 methop-toluenesulfonate)indole (1.98 g., 2 mol.) was dissolved in hot glacialacetic acid '(10 ml.). Trimethoxypropene, 1.0 g., 1 mol. and 200%) and48% aqueous HBr (1 mol.) were added.

The mixture was allowed to cool, then diluted with acetone. The solidwas collected and after two recrystallizations from methanol acidifiedwith HBr, the yield of purified dye was 0.44 g. (24%). This dye wasphotographically tested and found to provide especially useful directpositive materials.

. EXAMPLE 3 1, l dimethyl-2,2'-di-(4-pyridyl) -3 ,3'-indolocarbocyaninebromide, dihydrobrornide EXAMPLE 4 1,1 '-dimethyl-2,2-diphenyl-3,3'-benz [g] indolocarbocyanine bromide l-methyl-2-phenylbenz[g]indole(2.57 g., 2 mol. dissolved in hot glacial acetic acid (20 ml.).Trimethoxy= propene (2.0 g., 1 mol. and 200% was added, followed by thedropwise addition of 48% HBr (0.9 ml.). When the mixture had cooled, theproduct was precipitatd by the addition of ether and the sticky residuestirred with portions of ether until crystalline. After tworecrystallizations from methanol (acidified with acetic acid) the yieldof purified dye was 0.65 g. (21%), M.P. 230 C. dec.

The above prepared dye compound was photographically tested by the exactprocedure of Example 1. Referring to Table I, it will be seen that thedye of this example had a minimum density in exposed areas of 0.06, asensitivity range up to 685 m 4, and a maximum sensitivity at 640 mp,whereas the control sample similarly prepared and tested, but containingno spectral sensitizing dye, increasesin density with exposure. When adispersion of a phenolic cyan-forming coupler was incorporatedintheemulsion of this example and then this emulsion was photographicallytested as in above Example 1, it was found that there was no decrease insensitivity and excellent reversal results were obtained, whereas arelated dye 1,1- dimethyl-2,2'-diphenyl -3,3' indolocarbocyaninebromide, when substituted for the dye of this example in such emulsions,showed no reversal on testing. The results are shown in Table II.

9 EXAMPLE 2-phenyl-1,7-trimethyle'neindole (1.17 g., 2 mols.) wasdissolved in warm acetic acid ml.) and stirred as trimethoxypropene (1.0g., 1 mol. and 200%) was added, followed by 48% aqueous HBr (0.5 ml.)The mixture was allowed to stand at room temperature overnight. Theproduct was precipitated by addition of ether and washed with portionsof ether until crystalline. After one recrystallization from methanol,the yield of purified dye was 0.4 g. (14%), M.P. 213-4 C. dec.

This dye was photographically tested by the exact procedure ofExample 1. Referring to Table I, it will be seen that the dye of thisexample had a minimum density in the exposed areas of 0.11, asensitivity range up to 710 III/1., and a maximum sensitivity at 650 mWhen a dispersion of a phenolic cyan-forming coupler was incorporated inthe emulsion of this example and then this emulsion was photographicallytested as in above Example 1', it was found that there was only amoderate decrease in speed and that excellent reversal results wereobtained. However, the related dye1,1'-dimethyl-2,2-diphenyl-3,3'-indolocarbocyanine bromide, whensubstituted for the dye of this example in such emulsion," showed noreversal on testing. Table II lists the results.

EXAMPLE 6 1'-methyl-2,2',10-triphenyl-1,7 -trimethylene-3 ,3"-

indolocarbocyanine perchlorate,

Z-phenyl-1,7-trimethyleneindole-3-carboxaldehyde (0.8 g., 1 mol.) and1-methy1-3-methylenebenzyl-2-phenylindole (0.95 g., 1 ml.) weredissolved in hot acetic acid (10 ml.) and 48% aqueous HBr (0.4 ml.)added. The mixture was allowed to-cool, then 70% aqueous perchloric acid(0.3 ml.) in a little-ethanol added. The mixture was allowed to stand atroom temperature for severalhours, then the solid was collected andwashed alternately with benzene and methanol until the red impurity hadbeen removed. After two recrystallizations from methanol containing alittle HBr, the yield of purified dye was 0.33 g. (16%), M.P. 248-9 C.dec. p

This dye was photographically tested by the exact procedure ofExample 1. Referring to Table I, it will be seen that the dye of thisexample had a minimum density in the exposed areas of 0.08, asensitivity range up to 735 me, and a maximum sensitivity at 675 m Whena dispersion of a phenolic cyan-forming coupler was incorporated in theemulsion of this example and then this emulsion was photographicallytested as in above Example 1, it was found that there was no change inthe minimum density, the speed decreased moderately, and excellentreversal results were obtained, whereas related dye 1,1'-dimethyl-2,2',8-triphenyl-3,3'-indo1ocarbocyanine perchlorate, when substituted forthe dye of this example in such emulsion,

resulted in a substantial increase in the minimum density, the speeddecreased sharply, and reversal was unsatisfactory. The data are shownin Table II.

EXAMPLE 7 1,1'-dimethyl-2,2',12-triphenyl-3-benz[-g]indolo-3 indolocarbocyanine perchlorate 1- methyl 2phenylbenz[g]indole-3-carboxaldehyde (0.81 g., 1 mol.) and1-methyl-3-methylenebenzyl-2-phenylindole (0.93 g., 1 mol.) weredissolved in hot acetic acid (10 ml.) and 48% aqueous HBr solution (0.4ml.) added. When the mixture had cooled, 70% perchloric acid (0.3 ml.)was added. After standing overnight, the solid was collected, washedwith benzene then with methanol. After one recrystallization frommethanol acidified with HCl, the yield of purified dye was 0.45-g.(21%), M.P. 261-2 C. dec.

The above dye was photographically tested by the exact procedure ofExample 1. Referring to Table I, the minimum density in the exposedareas were found to be 0.14, the relative clear speed was indicated at1450, while the maximum sensitivity was 655 m This dye was foundmarkedly useful for the production of excellent direct positivephotographic materials.

EXAMPLE 8 Grams N-methyl-p-aminophenol sulfate 3.1 Sodium sulfite, des45 Hydroquinone 12 Sodium carbonate, des 67.5 1.9

Potassium bror nide Water to 1 liter.

- The light fogged'material thus obtained can be exposed 'to an imagewith light modulated by a Wrattan No.15

v vvfilter to give a direct positive image. Similar results are obtainedwhen the dye of Example 3 is substituted for the aforementioned dye ofthis example.

EXAMPLE 9 Seven pounds of a silver chloride gelatin emulsion containingthe equivalent of g. of silver nitrate was heated to 40 C. and the pHwas adjusted to 7.8. Eight cc. of full strength (40%) formalin solutionwas then added and the emulsion was held at 40 C for 10 minutes. At theend of the holding period, the pH was adjusted to 6.0 and 0.125 g. ofthe dye of Example 5 abovewas in corporated therein. The emulsion wasthen coated on a support, and the element so, obtained was found toprovide good direct positive images. .Similar results are obtained whenthe dye of Example 1 is substituted for the dye of this example. i I HBy substituting other dye compounds of the'invention', as defined inFormula I above, into the pr ocedureof the above examples generallysimilar fogged, direct positive photographic silver halide emulsions andphotographic elements may be prepared. For example, other effective dyecompounds of the inventioninclude 8-(2-naphthyl)- 2,2-diphenyl-1,7,1',7fditrimethylene-3,3 .indolocarbocy- 1 1 anine perchlorate and thecorresponding chloride, bromide, iodide, p-toluenesulfonate, etc. salts,1,l-dimethyl-l- (Z-naphthyl)-2,2'-diphenyl-3,3'benz[g]indolocanbocyanine perchlorate and the corresponding chloride,bromide, iodide, p-toluenesulfonate, etc. salts, 1,1-dimethyl2,2',l0-tripheny1-3 ,3-benz[g1indolocarbocyanine bromide and the correspondingchloride, iodide, p-toluenesulfonate, perchlorate, etc. salts, and thelike.

A number of the above prepared dye compounds were photographicallytested by the exact procedure of Example 1. The results as shown inTables 1 and 2 indicate that the dyes of the invention provide excellentdirect positive materials.

TABLE I Minimum Density Density Dye in Unin 1 Example cone, exposedExposed Sens. Sens. o. g mole Areas Areas Mam, mu Range, mp.

1 0. 269 1. 74 0. 635 to 680 0. 200 1. 98 0. 6 640 to 685 0.445 1 76 011 650 to 710 0.500 1 94 0 08 675 to 735 0.800 1 84 0 14 655 I Asindicated previously, the cyanine dyes of the in-' vention may be usedadvantageously in silver halide emulsions containing color couplers.This is quite unexpected since the known indole trimethine cyanine dyescannot be successfully used in the presence of color couplers. Thus, thedyes of Examples 4, 5 and 6 were added to an emulsion prepared asdisclosed in Example 1 with a color coupler, and compared with therelated prior art dyes. The data are shown in following Table II.

mixture was heated in an oil bath at 140 C. for 30 minutes. Themixture'was allowed to cool, diluted with water (500 ml.) and made basicby the addition of concentrated aqueous KOH solution. The oil whichseparated was extracted with ether, the extract dried over 'MgSO and theether evaporated. The residue was dissolved in hot EtOH ml.) and thesolution chilled. The solid which separated was collected, pressed asdry as possible on a filter, and washed with a very small volume of coldethanol. The yield of very pale yellow crystals was 19.9 g. (48% M.P.79-81 C. This material was used without further purification.

EXAMPLE 1 1 1 I l-me thyl-2-(4-pyridyl)indole l -methyl-2-(3-pyridylmetho p-toluenesulfonate)indole jl-methyl-Z-(3 pyridyl)indole (5.2 p 1mol) and pts methyl-ptolucnesnlfonate (6.6 g., 1 mol and 50%) werewarmed together over a small flame and stirred with a thermometer. At 3040 C., an exothermic reaction TAB LE II Minimum Denslty in Density inDye Conc Unexposed Exposed Sens. Max., Sens. Range, Dye g/m e DispersionSpeed Areas Areas mp. my

Ex. 4,. 1. 62 0.08 630 to 710 Ex. 4,- 1. 62 0.06 640 to 700 A 1. 66 0.05 630 to 685 A 1. 66 Increase in density with exposure 1. 76 0. 11 650to 710 1. 90 0. 24 645 to 695 1. 84 0. 08 635 v to 690 1. 88 1. 88

1. 94 0. 08 675 to 735 1. 88 0. 08 670 to 710 1. 84 0. 08 670 to 730 1.90 0. 13 640 to 675 DyeB-1,1-dimethyl-2,2,S-tripheny1-3,3'-indoloearbocyanine perchlorate.

Dispersion I-A dispersion of a phenolic cyan-forming coupler of the typedescribed in Weissberger et al. U.S. Patent-No. 2,474,293, issued June28, 1949, in 20 g. of d1-n -buty1phthalate, 272 g. of 10% gelatin and 20ml. (at 151% Alkanol B (a trade name for analkylnaphthalene-sodium-sulfonate by E. I. du Pont de Nernours and Thefollowing examples describe the preparation of various intermediatecompounds used in the preceding examples for preparing the cyanine dyesof the invention.

EXAMPLE 10 l-methyl-2-(3-pyridyl)indole MgSQ and ether evaporated. 4 h I100% phosphoric acid (50 g.) was heated to 100" C. and stirred as thecrude hydrazone' was added in small portions, at such a rate that thetemperature stayed 'be- EXAMPLE 13 1-methyl-2-phenylbenz[g]indoleZ-phen'yl-1H-benz[=g]indole (24.3 g., 1 mol) which may be preparedaccording to Patel and Tedde-r, 1.08. 1963, 45935,-colorobenzene (36ml.) and water were slurried tween l25-'135 C. When the addition wascomplete, the 7 5 in a flask fitted with'an efficient high-speedstirrer, a ther- 13 mometer and an additional funnel. 50% NaOH (38 ml.)was added and the mixture stir-red and heated to 63 C. The heating wasstopped and the mixture stirred vigorously as methyl sulfate (15.1 g.,0.12 ml.) was added slowly, at such a rate that the temperature stayedbetween 62-65 C. When the addition was complete, the mixture was stirreda further 30 minutes, then diluted to about 250 ml. with water. Thechlorobenzene was removed by steam distillation, the residue chilled,and the solid collected and washed well with water and dried. The crudematerial was dissolved in benzene, chromatographed on an alumina column,and the benzene evaporated. The yield of white crystals was 11.1 g.(43%), M.P. 138.5-1395" C.

EXAMPLE 14 l-methyl-Z-phenylbenz [g] indole-3 -carb oxaldehyde CHO f Me

Dimethylformamide (6.0 ml.) was placed in a flask and chilled in anicebath. P001 (3.0 ml.) was added dropwise, then 1-methyl-2-phenylbenz[g] indole (7.7 g.) in warm dimethylformamide (25 ml.) was added in smallportions, the temperature being kept below 20 C. during both additions.The mixture was warmed at 3540 C. for 45 minutes, then poured inice-water (250 ml.). After brief stirring, a heavy precipitateseparated. 5 N NaOH (40 ml.) was added in portions, with stirring, andthe mixture heated to boiling, then allowed to cool. The solid wascollected and washed thoroughly with water. The yield of colorlesscrystals was 8.1 g. (95%), M.P. 170171 C. This material was used for thepreparation of dyes without further purification.

Example 15 2-phenyl-7,7trimethyleneindole A mixture ofl-phenyl-l-e-thylideneamino-l,2,3,4-tetrahydroquinoline (25 g.) andpolyphosphoric acid (40 g.) was heated on a steam-bath and constantlystirred with a thermometer. The temperature rose slowly to 110 0., whena vigorous exothermic reaction started. The flask was placed in a coldwater bath as the temperature rose to about 210 C. When the mixture hadcooled somewhat, 250 ml. of water was added, the mixture heated toboiling then cooled. The aqueous layer was decanted and the residuewashed with water. The product was extracted with portions of boilingether, the extracts combined, and the ether evaporated. The residue wasstirred with 25 ml. of cold ether until a suspension of crystallinesolid was obtained. The solid was collected and washed with a smallvolume of ether. The yield was 5.0 g. (21%) M.P. 120-1 C. This materialwas used without further purification. In this example, the star-tingmaterial (1-phenyl-1-ethylidenamino-l,2,3,4-tet-rahydroquinoline) wasprepared by heating on a steam-bath for one hour a mixture of 1-amino-1,2,3,4-tetrahydroquinoline (63.8 g., 1 mol.) [which can beprepared by the method of Kost et al., Zhur Obs. Khim. 29, 1949-53(1959)] acetophenone (57.1 g., 1 mol) and glacial acetic acid (2 ml.).Ethanol (100 ml.)

14 was added and the mixture heated to boiling, when a clear solutionwas obtained. On chilling the solution, the product separated in largeyellow crystals, which were collected and washed with a little ethanol.Yield, 84.9 g. (79%), M.P. 83-84 C. This material was used withoutfurther purification.

EXAMPLE 16 2-phenyl-1,7atrimethyleneindole-3-carboxaldehyde \NX/Q UPhosphoryl chloride (4.2 ml.) was added slowly to dimethylformamide (10ml.), keeping the temperature below 20 C. by cooling in an ice-bath. Asolution of 2- phenyl-1,7-trimethylene-indole (8.0 g.) in warmdimethylformamide (20 ml.) was added slowly, maintaining the temperaturebelow 20 C. The mixture was warmed at 35-40 C. for 1 hour, then pouredinto water (250 ml.). 5 N sodium hydroxide (48 ml.) was added slowly,with stirring. The aqueous layer was decanted from the sticky materialwhich separated. The residue was boiled and stirred with ethanol (25ml.), then chilled. The solid was collected and washed with a smallvolume of ethanol. The yield was 5.75 g. (64%). This material was usedwithout further purification. A small sample, recrystallized fromethanol, had M.P. 143-4 C.

The photographic silver halide emulsion and other layers present in thephotographic elements made according to the invention can be hardenedwith any suitable hardener, including aldehyde hardeners such asformaldehyde, and mucochloric acid, aziridine hardeners, hardeners whichare derivatives of dioxane, oxypolysaccharides such as oxy starch or oxyplant gums, and the like. The emulsion layers can also containadditional additives, particularly those known to be beneficial inphotographic emulsions, including, for example, lubricating materials,stabilizers, speed increasing materials, absorbing dyes, plasticizers,and the like. These photographic emulsions can also contain in somecases additional spectral sensitizing dyes. Furthermore, these emulsionscan contain color forming couplers or can be developed in solutionscontaining couplers or other color generating materials. Among theuseful color formers are the monomeric and polymeric color formers,e.g., pyrazolone color formers, as well as phenolic, heterocyclic andopen chain couplers having a reactive methylene group. The color formingcouplers can be incorporated into the direct positive photographicsilver halide emulsion using any suitable technique, e.g., techniques ofthe type shown in Jelley et al., U.S. Patent 2,322,027, issued June 15,1943, Fierke et al., U.S. Patent 2,801,171, issued July 30, 1957,Fisher, U.S. Patents 1,055,155 and 1,102,028, issued Mar. 4, 1913, andJune 30, 1914, respectively, and Wilmanns, U.S. Patent 2,186,849, issuedJan. 9, 1940. They can also be developed using incorporated developerssuch as polyhydroxybenzenes, aminophenols, 3-pyrazolidones, and thelike.

Although the invention has been described in considerable detail withparticular reference to certain preferred embodiments thereof, it willbe understood that variations and modifications can be elfected withinthe spirit and scope of the invention as described hereinabove, and asdefined in the appended claims.

We claim:

1. A fogged direct positive photographic silver halide emulsioncontaining at least one cyanine dye compound selected from those havingtwo indole nuclei, each re- Ha I R R5 X wherein A represents asubstituent selected from the group consisting of a nonheterocyclic arylradical and a heterocyclic radical containing from 5 to 6 atoms, and theheteroatom is selected from the group consisting of nitrogen, sulfur,selenium and oxygen; R and R each represents a substituent selected fromthe group consisting of hydrogen, an alkyl radical, halogen and, takentogether, the atoms necessary to complete a fused nonheterocyclicaromatic ring having 6 carbon atoms; R represents an alkyl radical; Rrepresents a substituent selected from the values given for R and, takentogether with R an alkylene bridge; X represents an anion; and A R R Rand R each are selected from same values, respectively, as A, R R R andR and, Z and Y each represents a substituent selected from the groupconsisting of a hydrogen atom and an aromatic radical; at least one ofsaid indole nuclei containing a substituent selected from the groupconsisting of said heterocyclic radical, said fused non-heterocyclicaromatic ring and said alkylene bridge.

3. A direct positive photographic emulsion in accordance with claim 2wherein said dye compound is a trimethine dye wherein each of saidindole nuclei contains a substituent selected from the group consistingof said heterocyclic radical, said fused non-heterocyclic aromatic ringand said alkylene bridge.

4. A direct positive photographic emulsion in accordance with claim 2 inwhich said silver halide is present in the form of light fogged silverhalide grains.

5. A direct positive photographic emulsion in accordance with claim 2 inwhich said silver halide is present in the form of chemically foggedsilver halide grains.

6. A fogged direct positive photographic silver halide emulsioncontaining a dye selected from the group consisting of:1,l'-dimethyl2,2'-di-(3-pyridyl)-3,3 indolocarbocyanine salt;1,1-dimethyl-2,2'-di-(3-pyridyl metho salt)-3,3'-indolocarbocyaninesalt; 1,l'-dimethyl-2,2' diphenyl-3,3-benz[g]indolocarbocyanine salt;2,2'- diphenyl-1,7,1',7'-ditrimethylene-3,3' indolocarbocyanine salt;-methyl2,2,IO-triphenyl-l,7-trimethylene-3,3' indolocarbocyanine salt;1,1-dimethyl-2,2',12-triphenyl-S-benz [g] indolo-3'-indolocarbocyaninesalt; and 2,2-diphenyl- 1,7 ,l,7-ditrimethylene-3,3-indo1ocarbocyaninesalt. I 7. A direct positive photographic emulsion in accord- 1 6 ancewith claim 2containing 'a photographic color coupler.

8. A photographic element comprising a support coated with at least onelayer containing a direct positive photographic silver halide emulsionof claim 2.

' 9. A'p'hotographic element comprising a support coated with at leastone layer containing a direct positive photo-' graphic silverhalide'emulsion of claim 3. v

10. A direct positive, photographic emulsion in accordance with claim 2which comprises fogged silver halide grains, said grains being such thata test portion thereof, when coated as a photographic silver halideemulsion on a support to give a maximum density of at least about 1 uponprocessing for 6 minutes at about 68 F. in Kodak DK- developer, has amaximum density which is at least about 30% greater than the maximumdensity of an identical coated test portion which is processed for 6minutes at about 68 F. in Kodak DK-SO developer after being bleached forabout 10 minutes at about 68 F. in a bleach composition of:

Potassium cyanide-50 mg. Acetic acid (glacial)3.47 cc. Sodiumacetate-11.49 g. Potassium bromide1 19 mg. Water to 1 liter.

11. A direct positive, photographic emulsion in accordance with claim 2which comprises fogged silver halide grains, at least 95%, by Weight, ofsaid grains having a size which is within about 40% of the average grainsize.

12. A direct positive, photographic emulsion in accordance with claim 6which comprises fogged silver halide grains, said grains being such thata test portion thereof, when coated as a photographic silver halideemulsion on a support to give a maximum density of at least about 1 uponprocessing for 6 minutes at about 68 F. in Kodak DK-SO developer, has amaximum density which is at least about 30% greater than the maximumdensity of an identical coated test portion which is processed for 6minutes at about 68 F. in Kodak DK-SO developer after being bleached forabout 10 minutes at about 68 F. in a bleach composition of:

Potassium cyanide-50 mg. Acetic acid (glacial)-3.47 cc. Sodiumacetate-l1.49 g. Potassium bromidel 19 mg. Water to 1 liter.

13. A direct positive, photographic emulsion in accordance with claim 6which comprises fogged silver halide grains, at least 95%, by weight, ofsaid grains havinga size which is within about 40% of the average grainsize.

References Cited NORMAN G. TORCHIN, Primary Examiner R. E. FIGHTER,Assistant Examiner U.S. c1. X.R. 96-107;260240,

